1. Field of the Invention
The present invention relates to the administration of fluids, as well as medications into the subcutaneous (under the skin) area of a pet or other animal such as a dog, cat, etc. More particularly, the present invention relates to an improved method and apparatus for use in veterinary medical and animal research industries that features an improved catheter construction adapted to be placed subcutaneously, enabling convenient administration of fluids and medications into the animal""s body through the subcutaneous route without the use of needles (in one embodiment) by the owner of the animal in the animal""s home environment.
2. General Background of the Invention
As veterinary medical technology has improved, pets are living longer, healthier lives. However, as pets become older, a high percentage of them develop chronic kidney disease associated with old age. This disease is debilitating and eventually fatal. There are three important factors in the treatment of this disease. They are: change of diet, control of anemia and phosphorus levels in the blood, and the long term administration of subcutaneous or intravenous fluids. Of these, fluid administration is the most critical. Fluid administration works to increase the perfusion of the kidneys and excretion of uremic toxins. As this excessive fluid is eliminated, it will carry out uremic toxins that the body can no longer eliminate on its own. These factors have been recognized for over 50 years.
Special diets have been developed to restrict protein and the build up of toxic byproducts. Hormones and phosphate binders have been developed that can control the anemia as well as the elevated phosphorus levels. However, fluids are still the most important aspect of the treatment of this disease. Today, fluids are still administered the way they were fifty years ago. If the animal was hospitalized, the fluids would be administered through an I.V. catheter directly into a vein or given by subcutaneous injections with needles by a trained technician. However, once the patient was stabilized and ready to be released, the options were very limited. One option would be for the client to return with the pet every few days to the hospital to have subcutaneous or intravenous fluids administered by trained personnel. The other option would be for the client to be trained to administer the subcutaneous fluids at home using the conventional approach of multiple needle sticks and the injection of large volumes of fluids up to twice daily.
Fluid therapy had to be carried out by the administration of subcutaneous fluids in large volumes through a large-bore needle attached to an intravenous administration set or syringe. The volume of fluid required frequently exceeds 300 ml per day. This is equivalent to 10 ounces of fluids or 100 of the familiar 3 ml syringes used for routine injections. Because of the large volume of fluids being administered, multiple injections must be made up to twice daily. In general, pet owners are very squeamish about injecting drugs and fluids into their pets with needles. Health risk are present as well. It is impossible to sterilize the skin of the patient prior to each stick with the needle so the risk of infection is significant. Besides the pain and risk to the pet, there is risk of the owner sticking themselves with the needle and causing an infection. Disposal of the needles can also create a hazard to humans. Even when the client could tolerate this treatment of their pet, the pet would frequently withdraw and hide and the close relationship with their owner would suffer. Many owners would give up in frustration and the animal would suffer or be euthanized.
This subcutaneous fluid administration procedure and device was developed to address these problems. The combination of materials used, technique of implantation and maintenance, and subtle design characteristics have combined to produce a method and device that fills a glaring need in the treatment of animals with kidney and other chronic diseases. The implanted subcutaneous fluid administration tube can remain implanted for a year or more.
There has never been a usable device available to veterinarians for administration of fluids and medications to pets into the subcutaneous space, other than a hypodermic needle.
The method and apparatus of the present invention will improve the health and well-being of an animal as well as ease the owner""s fears about administering home treatment for their pet. It will result in less animals being euthanized for chronic but treatable diseases.
The method and apparatus of the present invention involves passing a specially designed catheter tube, composed of a material suitable for internal animal body use, through a small incision or opening in the skin and than tunneling the tube under the skin until it reaches the animal""s flank area.
The catheter tube can be stiffened by an internal stainless steel stylet which allows it to be gently forced through the subcutaneous space.
The catheter tube is generally passed from the neck area all the way to the flank location. Once placed, the stylet is withdrawn. The proximal end of the tube is capped with an injection port fitting, which can be penetrated by and connected to a short hollow plastic needleless injector. This injector can be attached either to an intravenous line and bag of I.V. fluids, or can be attached to a large syringe filled with fluids and/or medications.
Fluids or other medications can thus be administered to the pet by the owner without the need for an injection with a needle into the pet. This device also does not require the owner to handle a hypodermic needle. With the subcutaneous fluid tube technique of the present invention, the animal does not even know treatment is being administered. There are no needle sticks, and the fluids do not cause pain to the patient because they are the same concentration as normal body fluids and therefore not irritating. The fluids run into the patient at a rate of 100 ml (3 ⅓ ounces) per 1 xc2xd minutes thus making the treatment simple for the owner. Generally, the owner attaches a 1,000 ml fluid bag to a hanger attached to the top of a door. A standard IV administration set attaches the fluids to the implanted subcutaneous fluid administration tube using special needleless connectors. While sitting with the patient in their lap, the treatment can be finished in just 2-3 minutes. The bond and trust between the pet and the owner is not broken.
The present invention meets the needs of the veterinary industry by providing a product that will allow animals that would normally be euthanized to return to a relatively normal life. The subcutaneous fluid dispensing method and apparatus of the present invention provides an implantable catheter tube attached to a pad or skirt for suturing to the skin of the animal. A stylet of solid material such as stainless steel is provided. This stylet runs the length of the catheter tube and is attached to the tube by a screw on luer adapter. The stylet adds rigidity to the proximal end of the tube so that the combination of catheter tube and stylet can be passed through the subcutaneous tissues via a small incision or opening made in the skin of the patient.
The tube is fenestrated with small openings so that when fluids or medications are administered they can diffuse into the subcutaneous space along the length of the tube. For the administration of subcutaneous fluids, it is preferable that not more than the distal ⅔ of the catheter tube contains fenestrations so as to avoid fluids forming around the neck of the patient or leaking through the small incision or opening where the tube penetrates the skin.
There is a silicone or other non-reactive material skirt or pad which covers the area of entrance of the tube into the skin. This skirt provides a strong but comfortable surface to be secured to the animal. This skirt or pad protects the small exposed portion of the tube from working its way out from under the skin when the animal bends its neck down. The skirt is designed in such a manner that the area where the tube enters the skin is completely covered by the skirt. It also prevents the animal from grasping the tube with a claw and pulling the assembly out of the body. However, the incision or opening is preferably made between the animal""s shoulder blades and behind the skull so that the animal""s ability to claw, bite or scratch at the catheter is restricted.
Another alternative method of securing the catheter is to attach a small wrap of material around the silicone such as dacron that would allow the subcutaneous tissues to grow into the catheter and hold it in place indefinitely with no attachment directly to the skin.
Another method of attachment involves securing a small silicone bulb to the tubing just distal to the location where a small skirt is located on the proximal tube. Once the tube is inserted the bulb is pulled under the skin and a suture placed to close the skin over the bulb. The tube could not migrate into the patient because of the skirt on top of the skin and could not be pulled out of the patient because of the bulb under the skin. Advantages of the alternative methods of attachment are less discomfort to the patient and maintenance for the owner or veterinarian. Surgical time would also be decreased because fewer sutures would be required.
Another component of the device is a luer female hub that seals the tube and contains a rubber diaphragm. The hub is matched to a clip on plastic injection stylet that allows its small plastic hollow probe to be inserted through the diaphragm of the hub and into the fluid tube. Prongs of the injection stylet attach to the hub to make a solid connection while the medication or fluids are being administered. The I.V. set can be connected directly to the injection stylet. Once treatment is completed the wings of the injection stylet are compressed and the and the plastic hollow probe is withdrawn and recapped to protect its sterility.
Particularly, the present invention provides an improved method of administering fluids to an animal such as a pet (cat, dog, etc.). The method includes an initial step of forming one or more openings in the animal""s skin, at least one of the openings being positioned proximally on the animal""s body.
An elongated catheter is provided that includes a catheter wall, a central, fluid containing lumen, and proximal and distal end portions, the distal end portion having at least one and preferably a plurality of discharge openings.
A majority of the length of the catheter is placed in a subcutaneous space that extends proximally (eg. at the neck) to distally (eg. at the flank) on the animal""s body.
The method further contemplates an anchoring of the proximal portion of the catheter to the animal""s skin next to the incision.
Fluids are then transmitted to the animal via the catheter by removably connecting a fluids containing vessel to the catheter and discharging the fluids from the vessel into the subcutaneous space via the catheter.
The catheter wall is preferably provided with spaced apart wall openings that are positioned along a portion of its length, and further comprising the step of discharging the fluid into the subcutaneous space via the catheter wall openings, the openings preferably being positioned at the distal portion of the catheter.
The dispensing openings are preferably not positioned at the proximal portion of the catheter so that fluid does not flow over the neck area of the animal and out of the incision or opening.
In the preferred embodiment, an opening or an incision is positioned on the animal""s body at a location that restricts the animal""s ability to scratch, bite at or claw at the incision or opening, or at the proximal end portion of the catheter.
In the preferred embodiment, the incision or opening is positioned on or near the dorsal neck region of the animal.
The incision or opening can be positioned on the animal""s body generally in between the animal""s shoulder blades, making it difficult for the animal to reach the tube either by biting or clawing.
In one embodiment, two incision or openings are formed, one proximally and one distally. In this embodiment, a pair of forceps or other instrument can be used to pull the catheter from one incision or opening to the other.